Techniques for Determining Communication State Using Accelerometer Data

ABSTRACT

Techniques for communicating with a user on a network include receiving acceleration data that indicates acceleration of a mobile network node associated with a user of a network. A communication state for the user is determined based at least in part on the acceleration data. The communication state indicates a type of network communication suitable for communicating with the user. Network communications with the user are based on the communication state. Among other uses, such techniques allow a network communicating with a human through a mobile node carried by the human to infer from stopped or unusual motions when the human&#39;s ability to receive or act on communications is impaired or otherwise affected.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to using accelerometer data to determinecommunication state of a user on a network.

2. Description of the Related Art

Networks of general purpose computer systems connected by externalcommunication links are well known and widely used in commerce. Thenetworks often include one or more network devices that facilitate thepassage of information between the computer systems. A network node is anetwork device or computer system connected by the communication links.An “end node ” is a node that is configured to originate or terminatecommunications over the network. An “intermediate network node”facilitates the passage of data between end nodes.

Persons use networks to communicate in any of various ways, including byvoice and multimedia over analog and digital telephone networks.Communications mechanisms using computer networks include file transfer,web page viewing, electronic mail (“email”), on-line chat, chat-rooms,shared digital logs (blogs), instant messaging, voice over IP, and audioor video or multi- media streaming, among others. Many of thesecommunication mechanisms involve a “client” process operating on theperson's local computer exchanging data with a “server” processoperating on a remote computer on the network.

The client-server model of computer process interaction is widely knownand used. According to the client-server model, a client process sends amessage including a request to a server process, and the server processresponds by providing a service. The server process may also return amessage with a response to the client process. Often the client processand server process execute on different computer devices, called hosts,and communicate via a network using one or more protocols for networkcommunications. Network nodes are often hosts for client and serverprocesses. The term “server” is conventionally used to refer to theprocess that provides the service, or the host computer on which theprocess that provides the service operates. Similarly, the term “client”is conventionally used to refer to the process that makes the request,or the host computer on which the process that makes the requestoperates. As used herein, the terms “client” and “server” refer to theprocesses, rather than the host computers, unless otherwise clear fromthe context. In addition, the server process can be broken up to run asmultiple processes on multiple hosts (sometimes called tiers) forreasons that include reliability, scalability, and redundancy, but notlimited to those reasons.

Some communications, such as viewing web pages and email, are delayedcommunications that are completed at a later time when a second personsigns on to the network to receive the communication. It is becomingmore common for communications to be relatively immediate with multipleexchanges. Such communications require the presence of the remote partyon the network. With the proliferation of networks, a person absent onone network (an enterprise private network) might be present on anothernetwork (e.g., a cellular telephone network or the public Internet).

Presence data is used in several extant and emerging applications. Forexample, in instant messaging applications, such as AOL InstantMessenger (AIM) from America Online of Dulles, Va. and PresenceWorks ofPresenceWorks, Inc in Alexandria Va., presence data indicates theinstantaneous knowledge that someone is available online and reachablevia instant messaging.

More broadly, presence data indicates a dynamically changing set ofchannels, capabilities, characteristics, preferences and ability forremote persons to communicate and interact with each other over anetwork at the current time. Thus in the following, the terms “presence”and “present communication state” are used interchangeably. See forexample the document identified as request for comments (RFC) 2778 foundat a website of the Internet Engineering Task Force (IETF) found atdomain ietf.org. The entire contents of RFC 2778 are hereby incorporatedby reference as if fully set forth herein.

Presence data includes such present communicative states of availabilityas “online,” “offline,” “do not disturb,” “at lunch.” Some applicationsconsider other availability information as presence data, includinginformation that indicates, for a particular person, “try mobile phonefirst, then business line”, “always send e-mail” or “unavailable forconference calls, but available for webcasts.” In some applications,presence data may include physical location of the person such as “ontravel in London,” or “at home,” or “in office” or “at companyheadquarters,” as well as a network address.

In some applications, presence data indicates people on the same(virtual) location like a web page or a shared document at the sametime. In some applications, presence data indicates people who arewithin the same cell (the geographical area covered by a cellular phoneantenna). In some applications, presence data indicates location of aperson or facility based on a positioning system, such as the GlobalPositioning System (GPS) widely used in commerce and by the military.Geographic position is a communication state in the sense that oneperson is within sight or earshot of another person or node on thenetwork.

As used in the following, presence data indicates the communicationstate for a person at the current time and includes all sources of suchinformation, no matter how precise or reliable, including a person'splanned location or communicative state in a calendar database for thecurrent time. Predicted future communication states and recorded pastcommunication states are communication states that are not consideredwithin presence data.

Most applications that use presence data require a human user tomanually input data so the application can more accurately infer thehuman user's state. For example, even after the human user logs onto aninstant messaging service (which usually requires manual input but canbe automated), the service does not know whether the user is sitting ata desk and looking at the host's display device or not. The systeminfers that the user is present and attentive if the user has recentlytyped any information using the keyboard. The system assumes the user isidle if no keys are pressed for several minutes. An idle user may be inthe room attentive to a video or audio display on the host but doingsome other activity, such as reading a paper or talking on a telephone.Alternatively, the user may be gone away from the host and in nosituation to respond to network communications presented at that hostduring that time. To distinguish the two cases, the user must manuallyinput data that indicates the user is leaving the vicinity of thenetwork node and may be expected back in an estimated amount of time(e.g., out to lunch, “2 hour meeting,” “on vacation,” etc.) In thesesystems, the communicative state of a user is determined by manualinput.

While requiring manual input to infer communicative state is useful inmany circumstances, there are ever more circumstances in which suchmanual input is inconvenient or impossible. For example, a cellulartelephone is turned on, but another user of the cellular telephonenetwork has no information about whether the cellular telephone owner isavailable to communicate using the cellular telephone. The other usermust cause the telephone to ring, wait for no response, and infer thatthe owner is unavailable, wasting time better spend contacting analternate person who is available to talk. It is inconvenient for thecellular telephone owner to constantly press keys to notify the networkthat not only is the cellular telephone on, but the owner is currentlyavailable for communications using it.

Some emerging systems would benefit even more than the cellulartelephone system from communication state data that does not requiremanual input. For example, mobile ad hoc networks (MANets) involvemobile wireless routers that network with other fixed or mobile wirelessrouters with which they come into transmission range. The mobile routerscan be carried by humans, animals or vehicles, including robots, tointerface multiple electronic devices also carried. MANets haveapplications in tactical police and military and emergency medicalservices scenarios, including Search and Rescue. The mobile routers feedinformation to various control interfaces for the vehicles or variousdisplay elements for a human user or stimuli for animals. The routersalso receive and transmit to the network information from varioussensors or input devices operated by the user, such as the person, ananimal or the vehicle. The MANets allow different units to share moreinformation more quickly so that the multiple units can proceed as acoordinated whole.

If a particular human, animal, or vehicular user of the mobile routerloses the capacity to coordinate actions with the other units, then theother units would want to be made aware of this change in availabilityof that particular user. In some circumstances, communications with theparticular user would be affected, that is the communication state ofthe user has changed. In some circumstances, the user would be unable toprovide manual input to signal the change. For example, an animal or aninjured human or a maximally active human might not be able to provideneeded manual input. Communications are affected, for example, becauseif a particular user is unable to move, communications involving theuser's motion are wasteful of scare network resources. If a person isunconscious, then the person is incommunicado regardless of theintegrity of the person's electronic equipment. If a user is highlyactive dealing with a crisis, such as a burning home or hostile gunfire,the user is not available for non-crucial communications and is too busyto report this change in availability until the crisis has diminished.

The change in the communication state of the user leads to a change inthe types of communication that should be used. In some circumstances,tactical communications might be dropped and replaced with diagnosticcommunications to determine what is wrong with that particular user. Apulse sensor for a living user might be interrogated. Variouscomputerized systems or sensors on a vehicle would be interrogated. Ifremedial activity by the user could be determined, then it would bebeneficial to transmit information conveying the remedial activity tothe user on a channel the user is expected to receive (such as audio ifthe person is too consumed by crisis to view video).

In some circumstances, the user could become captured by hostile forces,and the information carried through the MANnet can be compromised. Itwould be desirable to know that the person's use of the network haschanged, i.e., the communication state for network communications haschanged, even though the person is unable to make any manual entries. Asa result of this change in communication state, it would be desirable tostop transmitting sensitive information and delete all sensitiveinformation stored on the devices carried by the person.

Based on the foregoing, there is a clear need for techniques todetermine the communicative state of users of network nodes withoutmanual input from the users and to communicate with the user based onthe communicative state.

The approaches described in this section could be pursued, but are notnecessarily approaches that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, the approaches describedin this section are not to be considered prior art to the claims in thisapplication merely due to the presence of these approaches in thisbackground section.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 is a block diagram that illustrates a network with data andservers for communicating based on communication state, according to anembodiment;

FIG. 2 is a flow diagram that illustrates at a high level a method forcommunicating based on communication state, according to an embodiment;

FIG. 3 is a graph that illustrates raw and processed acceleration data,according to an embodiment; and

FIG. 4 is a block diagram that illustrates a computer system upon whichan embodiment of the invention may be implemented.

DETAILED DESCRIPTION

A method and apparatus are described for communicating with a user on anetwork. In the following description, for the purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be apparent, however, toone skilled in the art that the present invention may be practicedwithout these specific details. In other instances, well-knownstructures and devices are shown in block diagram form in order to avoidunnecessarily obscuring the present invention.

In various embodiments, accelerometer data is used to infercommunicative state of a network user. Among other uses, such techniquesallow a network communicating with a human through a mobile node carriedby the human to infer from stopped or unusual motions that the human'sability to receive or act on communications is impaired or otherwiseaffected.

For purposes of illustration, embodiments of the invention are describedin the context of a MANet used by a military force, but the invention isnot limited to this context. In other contexts, other networks,including cellular telephone networks apply techniques of the presentinvention to support the same or different services.

1. Structural Overview

FIG. 1 is a block diagram that illustrates a network 100 forcommunicating with users, according to an embodiment. The network 100includes one or more subnetworks 102, intermediate network nodes 110 a,110 b, 110 c (collectively referenced hereinafter as intermediatenetwork nodes 110) connected to one or more network segments (e.g.,network segments 130 a, 130 b) with end nodes 120 a, 120 b, 120 c, 120 d(collectively referenced hereinafter as end nodes 120). The network 100includes communication state system 160, described in more detail below.One or more mobile network nodes are carried by users, such as users 150a, 150 b (collectively referenced hereinafter as users 150).

The subnetworks 102 include any network that connects a variety of usersof host computers, including, but not limited to, local area networks(LANs), wireless networks, wide-area networks (WAN), the Internet (anetwork of heterogeneous networks using the Internet Protocol, IP), andvirtual private networks. For the purposes of illustration, four endnodes 120 a, 120 b, 120 c, 120 d and three intermediate network nodes110 a, 110 b, 110 c are shown in FIG. 1. In other embodiments more orfewer end nodes and intermediate network nodes are included in network100.

For purposes of illustration, mobile end node 120 a is carried by user150 a and communicates by a wireless link with intermediate network node110 a. For example, user 150 a carries a laptop computer with a wirelessnetwork interface card as end node 120 a. As another example, user 150 acarries a cellular telephone that has a wireless link with a cellulartower that connects to an intermediate cellular network node 110 a.

Also for purposes of illustration, mobile intermediate network node 110c is carried by mobile user 150 b and communicates by a wireless linkwith intermediate network node 110 b. Mobile network node 110 c is alsoconnected to network segments 130 a, 130 b that are carried by user 150b. A network segment is a portion of a network that does not include anintermediate network node. Network segment 130 a connects mobileintermediate network node 110 c to mobile end nodes 120 c, 120 d thatare also carried by user 150 b. For example, a military troop carries apersonal router as intermediate network node 110 c connected by onenetwork segment 130 a to a wearable computer as one end node 120 c and adigital camera 120 d as a second end node 120 d. On network segment 130b, intermediate network node 110 c is connected to other end nodes (notshown) such as a controller for an ear-piece and heads-up display and aglobal positioning system (GPS) end node. In other embodiments, more orfewer users carry more or fewer network nodes and network segments.

According to the illustrated embodiment, at least one mobile nodecarried by a user 150 includes an accelerometer. For example, mobile endnode 120 a includes accelerometer 140 a, and mobile intermediate networknode 110 c includes accelerometer 140 b. In other embodiments, more orfewer or different mobile network nodes include an accelerometer.

Accelerometers are devices that measure acceleration, i.e., changes inspeed or direction experienced by the accelerometer. Digitalaccelerometers of small size and power requirements with a wide varietyof sensitivities and frequency responses are available commercially.Some small size accelerometers are micro-electromechanical systems(MEMS) accelerometers fabricated using techniques of integratedcircuits. See for example accelerometers described at the time of thiswriting at the Internet sites of, among others, Honeywell electronics(document index.shtml at web domain inertialsensor.com), or SiliconDesign Inc (documents index.html and tech.html at web domainsilicondesigns.com) or the Center of Wireless Integrated Microsystems(WIMS) at the University of Michigan (document Trans03.pdf in directory/˜jchae/pdf/ at web domain eecs.umich.edu), the entire contents of eachof which are hereby incorporated by references as if fully set forthherein. Among these accelerometers the capability is provided formeasuring accelerations as small as one hundred thousandth of g, where gis the acceleration of gravity, about 9.8 meters per second per second(m/s²), to accelerations as large as thousands of g, on time scalesincreasing from about a hundredth of a second.

Accelerometers are widely known and used in mobile devices to monitor orcontrol operation of such devices. For example, accelerometers are usedin automobile air-bag systems to detect crash conditions suitable fordeploying an air bag. In another example, an accelerometer is used in amobile computing device with a magnetic hard disk, such as a laptopcomputer. The accelerometer detects a dropped device so the hard diskcontroller can retract read heads from the hard disk surface and lockthe hard disk from rotating. These responses reduce or avoid damage tothe hard disk and the data stored on it when the dropped device hits theground or some other surface. Accelerometers are also used to detect andmonitor vibrations in heavy equipment and vehicles. To applicants'knowledge, no accelerometers are used or proposed to determine presenceon a network.

The network 100 includes the communication state system 160, whichdetermines the communication state of users at the end nodes of thenetwork 100, such as users 150 a, 150 b and a user (not shown) ofstationary end node 120 b. The communication state system 160 includes acommunication state server 162 and a library 164 of data that indicatesacceleration characteristics on one or more storage devices. Thecommunication state server 162 determines communication state of one ormore users based on acceleration data and controls the storage andretrieval of acceleration characteristic data in library 164. Forpurposes of illustration, communication state server 162 is shownseparate from nodes 110, 120; but in some embodiments, communicationstate server 162 resides in part or in whole on one or more of nodes110, 120 or other nodes (not shown) of subnetworks 102. Furthermore, forpurposes of illustration, one communication state server 162 isconnected to one storage device with library 164, but in otherembodiments, the library may be distributed or several data storagedevices connected directly to one or more communication state serverslike server 162, or connected indirectly to one or more servers throughsub-networks 102. Any communication state system known in the art may bemodified to serve as communication state system 160. In variousembodiments, network 100 includes more or fewer communication statesystems like system 160.

The library 164 of acceleration characteristics associates spectral orstatistical characteristics of acceleration data with corresponding useractivities. For example, the library 164 includes data that indicates afirst set of acceleration amplitude ranges in certain accelerationfrequency bands that is uniquely associated with human walking motion.As a further example, the library 164 includes data that indicates asecond set of acceleration amplitude ranges in different accelerationfrequency bands that is uniquely associated with human running motion.As a still further example, the library 164 includes data that indicatesa third set of acceleration amplitude ranges in different accelerationfrequency bands that is uniquely associated with off-road travel by aland vehicle in certain terrain.

For example, in a second illustrated embodiment, a definition isdeveloped for a user “activity state” by modeling that state as a seriesof motion events. Each motion event is characterized as a vectorincluding a duration of time, a positive acceleration event onset ineach of three directions, a maximum velocity event maturity in each ofthree directions, and a negative acceleration (deceleration) eventconclusion in each of three orthogonal directions. The orthogonaldirections can be expressed in Cartesian, spherical, or othercoordinates. A “running” activity state is then associated with someseries of motion event vectors. Similarly, a “walking,” “riding,”“stationary” or other activity state is associated with a series ofdifferent motion event vectors, as described in more detail in the nextsection with reference to FIG. 3. In other embodiments, a motion eventis a vector expressing duration, acceleration, maximum velocity anddeceleration in two dimensions, such as in a Cartesian plane or usingpolar coordinates, or in one dimension, such as acceleration magnitudeand speed.

2. Method of Using Accelerometer Data for Presence

FIG. 2 is a flow diagram that illustrates a method 200 for communicatingwith a user on a network based on accelerometer data, according to anembodiment. Although steps are indicated in a particular order in FIG.2, in other embodiments, the steps may be performed in a different orderor overlapping in time, or one or more steps may be omitted, or changedin some combination.

In step 210, acceleration is measured at a mobile node by anaccelerometer to produce raw acceleration data. As used here, the term“raw” acceleration data means the acceleration data output by theaccelerometer. In some embodiments raw data is an analog signal (such asprovided by the amplitude or frequency of a voltage signal). In someembodiments, raw data is a digital signal, such as an eight binary digit(bit) value that represents acceleration for a particular time interval(e.g., one hundredth of a second).

For example, in some embodiments during step 210, acceleration ismeasured at accelerometer 140 a on a cellular telephone serving as endnode 120 a carried by user 150 a. In some embodiments acceleration ismeasured at accelerometer 140 a on a hard disk drive in a mobilecomputer with a wireless network card that serves as end node 120 acarried or worn by user 150 a. As another example, an accelerometer 140b is included in a personal router that serves as intermediate networknode 110 c on a heavily instrumented human, animal or vehicular user 150b. In some embodiments, the network node that includes the accelerometerprocesses the raw acceleration data to produce processed accelerationdata.

Any processing of raw acceleration data known in the art at the time anembodiment of the invention is implemented may be used. For example, invarious embodiments the raw data is digitized, averaged over longer timeintervals, filtered, calibrated, Fourier transformed to produce one ormore spectral characteristics, statistically processed to produce one ormore other statistical characteristics, or processed in some combinationof these ways to produce the processed acceleration data. In someembodiments, the processed data consumes much less data storage spacethan the raw acceleration data and can be transmitted over network 100while consuming substantially fewer network resources than transmittingthe raw acceleration data.

For purposes of illustration, it is assumed that the raw and processedacceleration data for one direction are as depicted in FIG. 3. FIG. 3 isa graph 300 that illustrates traces 310, 350 of raw and processedacceleration data, respectively, according to this illustratedembodiment. The horizontal axis represents the time axis 302, inarbitrary units, for both traces 310, 350. Two vertical axes are used.One vertical axis represents an acceleration axis 304 in arbitrary unitsfor the trace 310 of raw acceleration data. The horizontal line 305indicates a zero acceleration value. A second vertical axis represents aspeed axis 308 in arbitrary units for the trace 350 of processedacceleration data. The time axis 302 indicates a zero speed value.

The trace 310 of raw data represents the raw acceleration data producedby an accelerometer, e.g., accelerometer 140 b. The data includes a timeof the trace (e.g., a start time for time axis 302) elapsed time alongaxis 302, and acceleration over a sample time scale for each of multiplesamples. It is assumed for purposes of illustration that the sample timescale is short compared to the time for a user activity to evolve. Insome embodiments, the raw acceleration data includes a location (notshown) or velocity (not shown) derived from integrating the accelerationvalues over time, or both. As can be seen in FIG. 3, the trace 310 ofraw acceleration data shows a time extent of variable but predominantlypositive acceleration indicated by the line segment 312 labeled “averageacceleration.” This time extent represents a time of average positiveacceleration, during which speed is increasing in the directionassociated with this raw data. As also can be seen in FIG. 3, the trace310 of raw acceleration data shows a time extent of variable butpredominantly negative acceleration indicated by the line segment 316labeled “average deceleration.” This time extent represents a time ofaverage negative acceleration, during which speed is decreasing in thedirection associated with this raw data. As also can be seen in FIG. 3,the trace 310 of raw acceleration data shows a time extent of lessvariable but near zero acceleration indicated by the line segment 314labeled “constant speed.” This time extent represents a time of averagezero acceleration, during which speed is constant at some maximum valuein the direction associated with this raw data.

The trace 350 of processed acceleration data represents the processedacceleration data produced by a processor, e.g., in end node 120 c,plotted as speed versus time. The data includes a time of the trace(e.g., a start time for time axis 302) elapsed time along axis 302, andspeed deduced from average acceleration over the time period of averageacceleration 312, average acceleration over the time period of constantvelocity 314, and average acceleration over the time period of averagedeceleration 316. The processed data also includes motion event duration352 from the beginning of the period of average acceleration to the endof the period of average deceleration. In some embodiments, theprocessed acceleration data includes a location (not shown). As can beseen in FIG. 3, the trace 350 of processed acceleration data shows alinear increase in speed during the time extent of average acceleration.As also can be seen in FIG. 3, the trace of processed acceleration datashows a linear decrease in speed during the time extent of averagedeceleration. As also can be seen in FIG. 3, the trace of processedacceleration data shows a constant speed during the time extent ofconstant speed. During this time, the speed is at some maximum value inthe direction associated with this raw data, as indicated by the maximumspeed tick mark 354 on the speed axis 308. The duration, averageacceleration, maximum speed, and average deceleration for the motionevent vector are derived from the processed data.

In step 220, acceleration data for a mobile node is received at acommunication state server 162. In various embodiments, the accelerationdata received in step 220 is raw or processed acceleration data or both.

For example, in some embodiments, a communication state server 162resident on end node 120 a receives raw acceleration data fromaccelerometer 140 a. In an illustrated embodiment, a computer serving asend node 120 a, receives raw acceleration data produced by accelerometer140 a and generates processed acceleration data which is sent to andreceived by communication state server 162 on a different node of thenetwork 100. In some embodiments, a communication state server 162resident on end node 120 c receives raw acceleration data fromaccelerometer 140 b across network segment 130 a. In some embodiments acomputer serving as end node 120 c, receives raw acceleration data fromaccelerometer 140 b and generates processed acceleration data, which isthen sent to and received by communication state server 162 on adifferent node of the network 100. In an illustrated embodiment,intermediate network node 110 c receives raw acceleration data fromaccelerometer 140 b and generates processed acceleration data, which isthen sent to and received by communication state server 162 on adifferent node of the network 100.

In step 230, communication state is determined based, at least in part,on the acceleration data received. The communication state indicates atype of network communication suitable for communicating with the user.

For example, in some embodiments, one communication state indicates thatthe user is walking and in possession of a cell phone. Thiscommunication state indicates that a call on a cell phone is anappropriate network communication, but that an instant message to theperson's desktop computer is not appropriate for the user's currentstate. The portion of the communication state that indicates that theuser is walking is based on the acceleration data and makes it unlikelythat the person is within view or hearing range of the user's desktopcomputer.

In some embodiments, one communication state indicates that the user iswalking and in possession of both a laptop computer and a beeper. Thiscommunication state indicates that a call on the beeper is anappropriate network communication, but that an instant message to theperson's laptop computer is not appropriate for the user's currentstate. The portion of the communication state that indicates that theuser is walking is based on the acceleration data and makes it unlikelythat the person currently has the laptop deployed for viewing.

In an illustrated embodiment, one communication state indicates that theuser 150 b is unconscious and in possession of a personal router(serving as intermediate network device 110 c) connected to wearablecomputer (serving as end node 120 c) and a digital camera (serving asend node 120 d) on network segment 130 a and a controller for anear-piece and heads-up display and a global positioning system (GPS) endnode on network segment 130 b. The user is determined to be unconsciousbased on the acceleration data that indicates either no movement at all,or movement that is entirely due to a land vehicle moving over terrainin the user's vicinity, as determined by the GPS. This communicationstate indicates that a loud signal on the ear-piece is an appropriatenetwork communication to possibly rouse a sleeping troop, if warranted,but that a visual message to the troop's heads-up display is notappropriate for the user's current state. If the user does not respondto the ear-piece signal, then the user's state is changed, toinjured-unconscious to indicate that the troop could not be roused by aloud audio signal to the troop's ear-piece.

In an illustrated embodiment, the communicative state is determined froma group including, among others, communication states that indicate acombination of one or more of the following states: a persistentlymotionless living user who is not likely to be available for mostnetwork communication; a passive passenger living user who is movingonly passively with a moving vehicle and who is not likely to beavailable for most network communication; a mildly active (e.g.,shifting, head or hand moving) living user who is likely to be availablefor any network communication; a moderately active (e.g., walking)living user who is likely to be available for some networkcommunication; a strongly active (e.g., running) living user who islikely to be available only for certain most crucial networkcommunications; a normally functioning vehicular user that is likely tobe available for normal network communications; and an abnormallyfunctioning vehicular user that is likely to be available only fordiagnostic network communications; an unreliable communication channel;and a network node with compromised security.

In another embodiment, the activity states are associated withcommunication states as follows. When the user activity state isstationary, then the user can receive e-mail. When the user activitystate is moving very fast but not riding, then the user can receivevoice calls. When the user activity state is moving fast by riding, thenany form of short communications with the user is acceptable. When theuser activity state is unexpectedly not moving, then open a voice callwith a team member to check on the user. When the user activity stateindicates a fast fall towards earth followed by a sudden stop, then anemergency call is placed to send emergency services to the userlocation. When the user activity state is moving fast, then reduce thepacket size and data rate of IP packets to increase reliability. Whenthe user activity state is moving slow, then increase packet size anddata rate of IP packets to increase throughput.

Any method may be used to determine the communication state based on theacceleration data. In an illustrated embodiment, the server 162 mapsactivity state to network traffic types. In other embodiments, server162 or another server (not shown) maps activity state to other meaningsfor other purposes. In the illustrated embodiment, the mappingassociates an index table of “network address x” with “user y.” Server162 determines that “user y” is in “activity state z.” Server 162 thendetermines that “suitable communications are types a, b or c”. Thus,server 162 formulates and serves up communication state information for“user y” using library 164. For example, in some embodiments, server 162determines proper forms of communications (e-mail, voice call, instantmessenger (IM), pager, etc.).

In some embodiments, multiple different servers on the same or differentnode perform the functions of server 162. For example, an activity stateserver determines user y is associated with activity state z. Acommunications broker server associates user y with network addressesx1, x2, x3, x4 for a cell phone network, pager network, and various IPclients, and determines which of these addresses is best to use for thecurrent activity state of the user y. In some embodiments, thecommunications broker uses other sources of “presence” information inmaking its determination, such as login information or the fact that theuser just sent an IM message a few seconds earlier.

In other embodiments, step 230 includes predicting future communicationstates based on the acceleration data. For example, based on a currentposition of user 150 a and rate of movement from the accelerometer data,the communication state server 162 determines that the user 150 a isabout to leave an area of coverage for wireless communications overintermediate network node 110 a. In some embodiments, server 162 alsodetermines that user 150 a is expected to be incapable of reliablenetwork communications in the near future because the measuredaccelerations perturb an orientation of an antenna used by end node 120a to communicate with intermediate node 110 a. In some embodiments,server 162 also determines that user 150 a is expected to be incapableof any network communication after that time. In some embodiments,server 162 also determines that user 150 a is expected to come intobetter range of a different intermediate network node (e.g.,intermediate network node 110 b) when the user moves out of range ofintermediate network node 110 a.

In an illustrated embodiment, step 230 includes steps 232, 234, 236. Instep 232, one or more characteristics of the acceleration data aredetermined. For example, in an illustrated embodiment, a histogram ofhalf-second averaged accelerations accumulated over 45 seconds isdetermined based on the raw or processed acceleration data received instep 220 for the accelerometer 140 b on personal router serving asintermediate network node 110 c. In a second illustrated embodiment, aseries of motion event vectors are determined.

In step 234, the characteristic of the acceleration data are matched tocharacteristics in a library of acceleration characteristics associatedwith different user activities. For example, the histogram computed instep 232 is compared to one or more histograms in library 164 that areassociated with different human, animal and vehicular user activities.In a second illustrated embodiment, the series of motion event vectorsare associated with a user activity state, such as “stationary,”“walking,” “running,” “riding,” “falling,” etc.

In an illustrated embodiment, library 164 includes histograms for: anunconscious human user; a mildly active human user who is occasionallyshifting weight or moving hands or arms; a moderately active human userwho is walking; and a strongly active human who is running or moving aheavy load. In the illustrated embodiment, library 164 includeshistograms for an unconscious animal user, a moderately active animaluser, and a stressed animal user. In the illustrated embodiment, library164 includes, for each of several vehicles, histograms for one or morenormal operating conditions, including land operations over differenttypes of terrain, and one or more abnormal operating conditions, such asimmobilized vehicles, vehicles with damaged wheels or supports orstructures, and collisions.

It is assumed, for purposes of illustration, that, during step 234, thehistogram of half-second averaged accelerations accumulated over 45seconds based on the raw or processed acceleration data fromaccelerometer 140 b carried by human user 150 b matches most closely alibrary histogram for a land vehicle moving over rocky,vegetation-sparse terrain. When the vehicular motion is subtractedbecause the user 150 b is known to be a human, not a vehicle, theremaining signal matches most closely that of an unconscious human user.

In step 236, the current communication state is determined based, atleast in part, on the user activity associated with the matchedacceleration characteristic. For example, based on data (not shown) thatassociates intermediate node 110 c with human user 150 b, and based onthe determination during step 234, a communication state is determinedthat indicates that the user 150 b is unconscious and in possession of apersonal router (intermediate network device 110 c) connected towearable computer (node 120 c) and a digital camera (node 120 d) onnetwork segment 130 a and a controller for an ear-piece and heads-updisplay and a global positioning system (GPS) end node on networksegment 130 b. In the second illustrated embodiment, the user activitystate “unexpectedly not moving,” indicates a voice call should be openedwith a team member to check on the user, and packet size and data rateof IP packets should be increased to increase throughput.

In some embodiments, step 230 includes sending data that indicates thecommunication state to the mobile node. For example, step 230 includessending data to mobile end node 120 a that indicates that the node ismoving out of range of intermediate network node 110 a.

In step 250, communication with the mobile node is based on thecommunication state. For example, in some embodiments, if thecommunication state indicates an abnormally functioning vehicle, thenstep 250 includes providing reduced services to a mobile network node onthe vehicle and adding communications to interrogate diagnostic systemson the vehicle.

In the illustrated embodiment, communication with user 150 b is effectedby a loud signal on the ear-piece as an appropriate networkcommunication to possibly rouse a sleeping troop, if warranted, becausea visual message to the troop's heads-up display is not appropriate forthe current communication state.

If the user 150 b does not respond to the ear-piece signal, then theuser's state is changed, to injured-unconscious that indicates that thetroop could not be roused by a loud audio signal to the troop'sear-piece. In various embodiments, during step 250, communications withuser 150 b is suspended or diverted, depending on a protocol for theembodiment. In some embodiments, if the communication state indicates aninjured human, then step 250 includes providing reduced services to amobile network node carried by the human and adding communications tointerrogate diagnostic systems for the human, such as sensors for pulse,blood pressure and body temperature of the human user.

In some embodiments, the communication state is determined to becompromised communications, based at least in part on the accelerationdata. For example, if it is determined that no friendly vehicle is inthe vicinity of the user 150 b as determined by the GPS (not shown) onnetwork segment 130 b, then it can reasonably be inferred that the user150 b or user equipment 110 c, 130 a, 130 b, 120 c, 120 d, or both, havebeen captured by hostile forces and are being transported by landvehicle over the specified terrain. In various embodiments, sensitivedata is no longer communicated to intermediate network node 110 c, orsensitive data stored on one or more nodes carried by user 150 b (e.g.,nodes 110 c, 120 c, 120 d) is deleted, or both.

In some embodiments, step 250 includes sending data that indicates thecommunications state to the mobile node. For example, step 250 includessending data to mobile intermediate network node 110 c that indicatesthe compromised communication state. In response, one or more nodescarried by user 150 b deletes sensitive data.

In some embodiments, a network node is configured based on thecommunication state. For example, based on a communication state thatindicates unreliable communications, e.g., due to antenna accelerationsat an outer range of a wireless intermediate network node such as node110 b, a network node is configured to use a reduced value for a networkconfiguration parameter for a maximum size of data packets communicatedover the network (e.g., the maximum transmission unit, MTU)

In the second illustrated embodiment, the user activity state“unexpectedly not moving,” causes a voice call to be opened with a teammember to check on the user, and causes packet size and data rate of IPpackets to be increased to increase throughput.

In an illustrated embodiment, step 250 includes steps 252, 254. In step252, one or more routing policies are determined based on thecommunication state. For example, in some embodiments, it is determinedto use a network policy appropriate for unreliable communications. Anetwork policy is a set of rules for routing data packets on a network.For example, a particular network policy for unreliable transmissions isdetermined base on the communication state.

In step 254, a network node is configured based on the routing policy.For example, network node 110 b is configured to use a reduced value MTUas part of the particular network policy.

3.0 Implementation Mechanisms—Hardware Overview

FIG. 4 is a block diagram that illustrates a computer system 400 uponwhich an embodiment of the invention may be implemented. Computer system400 includes a communication mechanism such as a bus 410 for passinginformation between other internal and external components of thecomputer system 400. Information is represented as physical signals of ameasurable phenomenon, typically electric voltages, but including, inother embodiments, such phenomena as magnetic, electromagnetic,pressure, chemical, molecular atomic and quantum interactions. Forexample, north and south magnetic fields, or a zero and non-zeroelectric voltage, represent two states (0, 1) of a binary digit (bit). Asequence of binary digits constitutes digital data that is used torepresent a number or code for a character. A bus 410 includes manyparallel conductors of information so that information is transferredquickly among devices coupled to the bus 410. One or more processors 402for processing information are coupled with the bus 410. A processor 402performs a set of operations on information. The set of operationsinclude bringing information in from the bus 410 and placing informationon the bus 410. The set of operations also typically include comparingtwo or more units of information, shifting positions of units ofinformation, and combining two or more units of information, such as byaddition or multiplication. A sequence of operations to be executed bythe processor 402 constitute computer instructions.

Computer system 400 also includes a memory 404 coupled to bus 410. Thememory 404, such as a random access memory (RAM) or other dynamicstorage device, stores information including computer instructions.Dynamic memory allows information stored therein to be changed by thecomputer system 400. RAM allows a unit of information stored at alocation called a memory address to be stored and retrievedindependently of information at neighboring addresses. The memory 404 isalso used by the processor 402 to store temporary values duringexecution of computer instructions. The computer system 400 alsoincludes a read only memory (ROM) 406 or other static storage devicecoupled to the bus 410 for storing static information, includinginstructions, that is not changed by the computer system 400. Alsocoupled to bus 410 is a non-volatile (persistent) storage device 408,such as a magnetic disk or optical disk, for storing information,including instructions, that persists even when the computer system 400is turned off or otherwise loses power.

Information, including instructions, is provided to the bus 410 for useby the processor from an external input device 412, such as a keyboardcontaining alphanumeric keys operated by a human user, or a sensor. Asensor detects conditions in its vicinity and transforms thosedetections into signals compatible with the signals used to representinformation in computer system 400. Other external devices coupled tobus 410, used primarily for interacting with humans, include a displaydevice 414, such as a cathode ray tube (CRT) or a liquid crystal display(LCD), for presenting images, and a pointing device 416, such as a mouseor a trackball or cursor direction keys, for controlling a position of asmall cursor image presented on the display 414 and issuing commandsassociated with graphical elements presented on the display 414.

In the illustrated embodiment, special purpose hardware, such as anapplication specific integrated circuit (IC) 420, is coupled to bus 410.The special purpose hardware is configured to perform operations notperformed by processor 402 quickly enough for special purposes. Examplesof application specific ICs include graphics accelerator cards forgenerating images for display 414, cryptographic boards for encryptingand decrypting messages sent over a network, speech recognition, andinterfaces to special external devices, such as robotic arms and medicalscanning equipment that repeatedly perform some complex sequence ofoperations that are more efficiently implemented in hardware.

Computer system 400 also includes one or more instances of acommunications interface 470 coupled to bus 410. Communication interface470 provides a two-way communication coupling to a variety of externaldevices that operate with their own processors, such as printers,scanners and external disks. In general the coupling is with a networklink 478 that is connected to a local network 480 to which a variety ofexternal devices with their own processors are connected. For example,communication interface 470 may be a parallel port or a serial port or auniversal serial bus (USB) port on a personal computer. In someembodiments, communications interface 470 is an integrated servicesdigital network (ISDN) card or a digital subscriber line (DSL) card or atelephone modem that provides an information communication connection toa corresponding type of telephone line. In some embodiments, acommunication interface 470 is a cable modem that converts signals onbus 410 into signals for a communication connection over a coaxial cableor into optical signals for a communication connection over a fiberoptic cable. As another example, communications interface 470 may be alocal area network (LAN) card to provide a data communication connectionto a compatible LAN, such as Ethernet. Wireless links may also beimplemented. For wireless links, the communications interface 470 sendsand receives electrical, acoustic or electromagnetic signals, includinginfrared and optical signals, that carry information streams, such asdigital data. Such signals are examples of carrier waves.

The term computer-readable medium is used herein to refer to any mediumthat participates in providing instructions to processor 402 forexecution. Such a medium may take many forms, including, but not limitedto, non-volatile media, volatile media and transmission media.Non-volatile media include, for example, optical or magnetic disks, suchas storage device 408. Volatile media include, for example, dynamicmemory 404. Transmission media include, for example, coaxial cables,copper wire, fiber optic cables, and waves that travel through spacewithout wires or cables, such as acoustic waves and electromagneticwaves, including radio, optical and infrared waves. Signals that aretransmitted over transmission media are herein called carrier waves.

Common forms of computer-readable media include, for example, a floppydisk, a flexible disk, a hard disk, a magnetic tape, or any othermagnetic medium, a compact disk ROM (CD-ROM), or any other opticalmedium, punch cards, paper tape, or any other physical medium withpatterns of holes, a RAM, a programmable ROM (PROM), an erasable PROM(EPROM), a FLASH-EPROM, or any other memory chip or cartridge, a carrierwave, or any other medium from which a computer can read.

Network link 478 typically provides information communication throughone or more networks to other devices that use or process theinformation. For example, network link 478 may provide a connectionthrough local network 480 to a host computer 482 or to equipment 484operated by an Internet Service Provider (ISP). ISP equipment 484 inturn provides data communication services through the public, world-widepacket-switching communication network of networks now commonly referredto as the Internet 490. A computer called a server 492 connected to theInternet provides a service in response to information received over theInternet. For example, server 492 provides information representingvideo data for presentation at display 414.

The invention is related to the use of computer system 400 forimplementing the techniques described herein. According to oneembodiment of the invention, those techniques are performed by computersystem 400 in response to processor 402 executing one or more sequencesof one or more instructions contained in memory 404. Such instructions,also called software and program code, may be read into memory 404 fromanother computer-readable medium such as storage device 408. Executionof the sequences of instructions contained in memory 404 causesprocessor 402 to perform the method steps described herein. Inalternative embodiments, hardware, such as application specificintegrated circuit 420, may be used in place of or in combination withsoftware to implement the invention. Thus, embodiments of the inventionare not limited to any specific combination of hardware and software.

The signals transmitted over network link 478 and other networks throughcommunications interface 470, which carry information to and fromcomputer system 400, are exemplary forms of carrier waves. Computersystem 400 can send and receive information, including program code,through the networks 480, 490 among others, through network link 478 andcommunications interface 470. In an example using the Internet 490, aserver 492 transmits program code for a particular application,requested by a message sent from computer 400, through Internet 490, ISPequipment 484, local network 480 and communications interface 470. Thereceived code may be executed by processor 402 as it is received, or maybe stored in storage device 408 or other non-volatile storage for laterexecution, or both. In this manner, computer system 400 may obtainapplication program code in the form of a carrier wave.

Various forms of computer readable media may be involved in carrying oneor more sequence of instructions or data or both to processor 402 forexecution. For example, instructions and data may initially be carriedon a magnetic disk of a remote computer such as host 482. The remotecomputer loads the instructions and data into its dynamic memory andsends the instructions and data over a telephone line using a modem. Amodem local to the computer system 400 receives the instructions anddata on a telephone line and uses an infra-red transmitter to convertthe instructions and data to an infra-red signal, a carrier wave servingas the network link 478. An infrared detector serving as communicationsinterface 470 receives the instructions and data carried in the infraredsignal and places information representing the instructions and dataonto bus 410. Bus 410 carries the information to memory 404 from whichprocessor 402 retrieves and executes the instructions using some of thedata sent with the instructions. The instructions and data received inmemory 404 may optionally be stored on storage device 408, either beforeor after execution by the processor 402.

4.0 Extensions and Alternatives

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

1. (canceled)
 2. An apparatus comprising: a memory including anacceleration characteristic associated with a human walking motion; anaccelerometer configured to generate data indicative of changes inmotion experienced by the apparatus; and a processor configured toidentify the human walking motion based at least on a comparison of thedata indicative of changes in motion experienced by the apparatus to thecharacteristic associated with the human walking motion.
 3. Theapparatus of claim 2, wherein the acceleration characteristic includes aset of acceleration amplitude ranges associated with human walkingmotion.
 4. The apparatus of claim 2, wherein the accelerationcharacteristic includes at least one acceleration frequency band.
 5. Theapparatus of claim 2, wherein the acceleration characteristic includes apositive acceleration event onset in each of three directions and theacceleration characteristic includes a negative acceleration event onsetin each of three directions.
 6. The apparatus of claim 5, wherein thememory includes a vector including a duration of time and the positiveacceleration event onset or the negative acceleration event onset. 7.The apparatus of claim 5, wherein the three directions for the positiveacceleration event onset or the three directions for the negativeacceleration event onset are expressed in Cartesian coordinates orspherical coordinates.
 8. The apparatus of claim 2, wherein theacceleration characteristic associated with human walking motion is afirst acceleration characteristic, the memory including a secondacceleration characteristic associated with a human running motion, theprocessor configured to identify the human running motion based at leaston the comparison of the data indicative of changes in motionexperienced by the apparatus to the characteristic associated with thehuman running motion.
 9. The apparatus of claim 2, further comprising: adisplay configured to present a visual message based on the humanwalking motion.
 10. The apparatus of claim 2, wherein the processor isconfigured to generate an alert based on the comparison.
 11. Theapparatus of claim 10, wherein the alert includes an audio signal.
 12. Amethod comprising: receiving, from an accelerometer, data indicative ofchanges in motion experienced by an apparatus; performing a comparisonof a library of acceleration characteristics associated withcorresponding user activities to the data indicative of changes inmotion; and determining a state of a user of the apparatus based atleast on the comparison.
 13. The method of claim 12, wherein the stateof the user corresponds to a human walking motion or a human runningmotion.
 14. The method of claim 12, wherein the library of accelerationcharacteristics includes a first set of acceleration amplitude rangesassociated with human walking motion and a second set of accelerationamplitude ranges associated with human running motion.
 15. The method ofclaim 12, wherein the library of acceleration characteristics includesacceleration frequency bands.
 16. The method of claim 12, wherein atleast one of acceleration characteristic in the library of accelerationcharacteristics includes a positive acceleration event onset in each ofthree directions and the acceleration characteristic includes a negativeacceleration event onset in each of three directions.
 17. The method ofclaim 16, wherein the at least one acceleration characteristic includesa vector including a duration of time and the positive accelerationevent onset or the negative acceleration event onset.
 18. The method ofclaim 12, further comprising: generating an alert based on thecomparison.
 19. A non-transitory computer readable medium includinginstructions that when executed are configured to: receive dataindicative of changes in motion experienced by an apparatus; perform acomparison of a library of acceleration characteristics associated withcorresponding user activities to the data indicative of changes inmotion; and determine a state of a user of the apparatus based at leaston the comparison.
 20. The non-transitory computer readable medium ofclaim 19, wherein the state of the user corresponds to a human walkingmotion or a human running motion.